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Search found 4 results on 1 pages for 's2k'.

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• What is an s2k algorithm?

  - by WilliamKF

  What is the definition of an s2k algorithm? For example, "PBKDF2(SHA-1)" is an s2k algorithm. Here is some Botan code that refers to s2k: AutoSeeded_RNG rng; std::auto_ptr<S2K> s2k(get_s2k("PBKDF2(SHA-1)")); s2k->set_iterations(8192); s2k->new_random_salt(rng, 8); SymmetricKey bc_key = s2k->derive_key(key_len, "BLK" + passphrase); InitializationVector iv = s2k->derive_key(iv_len, "IVL" + passphrase); SymmetricKey mac_key = s2k->derive_key(16, "MAC" + passphrase); Also, what is a 'salt' in s2k?

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• What does 'salt' refer to in string-to-key (s2k) specifier?

  - by WilliamKF

  What does 'salt' refer to in string-to-key (s2k) specifier? It appears to be a random number generator to shake things up, but I would like to know what 'salt' stands for? For example it is written: 3.6.1.2. Salted S2K This includes a "salt" value in the S2K specifier -- some arbitrary data -- that gets hashed along with the passphrase string, to help prevent dictionary attacks. Octet 0: 0x01 Octet 1: hash algorithm Octets 2-9: 8-octet salt value Salted S2K is exactly like Simple S2K, except that the input to the hash function(s) consists of the 8 octets of salt from the S2K specifier, followed by the passphrase. But salt is not defined, although its meaning seems clear.

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• computing matting Laplacian matrix of an Image

  - by ajith

  hi everyone, i need to compute Laplacian Matrix-L for an image(nXn) in opencv...computing goes as follows.......... dij - 1/|wk|{[1+1/(e/|wk|+s2)][(Ii-µk)*(Ij -µk)]}.... for all(i,j)?wk,summing over k yields (i,j)th element of L. where Here dij is the Kronecker delta,µk and s2k are the mean & variance of intensities in the window wk around k,and |wk| is the number of pixels in this window.wk is 3X3 window... here am not clear about 2 things... 1.what ll be the size of L?nXn or (nXn)X(nXn)?? 2.how to select Ii and Ij separately in 2D image?

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• Null Safe dereferencing in Java like ?. in Groovy using Maybe monad

  - by Sathish

  I'm working on a codebase ported from Objective C to Java. There are several usages of method chaining without nullchecks dog.collar().tag().name() I was looking for something similar to safe-dereferencing operator ?. in Groovy instead of having nullchecks dog.collar?.tag?.name This led to Maybe monad to have the notion of Nothing instead of Null. But all the implementations of Nothing i came across throw exception when value is accessed which still doesn't solve the chaining problem. I made Nothing return a mock, which behaves like NullObject pattern. But it solves the chaining problem. Is there anything wrong with this implementation of Nothing? [http://github.com/sathish316/jsafederef/blob/master/src/s2k/util/safederef/Nothing.java] As far as i can see 1. It feels odd to use mocking library in code 2. It doesn't stop at the first null. 3. How do i distinguish between null result because of null reference or name actually being null? How is it distinguished in Groovy code?

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